In recent years, to achieve both objectives of improving the degree of integration and increasing on-state current of a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), a fin type MOSFET (hereinafter referred to as “fin type transistor”) is proposed. In the fin type transistor, a fin, which extends in one direction and has a convex shape, is formed on an upper surface of a semiconductor substrate and a gate electrode extending in another direction is provided to cross over the fin. Thereby a circumferential portion of a portion of the fin surrounded by the gate electrode becomes a channel region, so that the channel width can be increased without increasing an element area.
From a viewpoint of utilizing design resources, there is a need that a fin type transistor and a normal planar MOSFET (hereinafter referred to as “planar transistor”) are mixed on the same substrate. However, it is difficult for conventional techniques to separately form a fin type transistor and a planar transistor by a common process.